Detectors of high-energy and ionizing radiations are used in various applications. Such detectors, for example, include ion chambers, proportional counters, Geiger-Mueller counters, and scintillation counters, and may be used to detect high energy photons, such as X-rays or gamma-rays. As such, gamma-rays have been used to measure the density and level of fluids in a vessel by using a gamma-ray source positioned opposite or near a gamma-ray detector. Gamma-ray density and level measurements are useful where the materials measured are hazardous, extremely hot, or where direct contact measurements are otherwise not possible. Additionally, the source and detector are mounted outside the vessel, and no modification to the vessel is required. Gamma-rays emitted by a source may be absorbed or attenuated by the vessel and the material in the vessel. The strength of the gamma radiation reaching a detector may be used to indicate the density or level of a fluid in a vessel based upon the intensity of the source.
When measuring fluid level, for example, gamma-ray emitters and/or detectors may be positioned on or near a vessel, where the presence or absence of a signal (or a nominal low signal) may indicate the presence or absence of a fluid near the source and detector. With respect to fluid density, fluid near the gamma-ray source and detector may absorb or attenuate gamma-rays emitted by the source. For example, a high radiation count may indicate a low fluid density, while a low count may indicate a high fluid density.
A primary variable with respect to the amount of gamma-rays emitted from the source that reach the detector is the fluid contained within the vessel. A percentage of the gamma-rays emitted by the source are absorbed or attenuated by fluid and, therefore, do not reach the detector. Thus, the counting rate of the output signal from a photo multiplier tube of a detector may be related to the density of fluid through which the rays must pass to reach the detector and the intensity of the gamma radiation source.
Various factors, however, have been known to affect the reliability of the high-energy and ionizing radiation detectors. For example, a detector working within the industrial environment, as described above, may be expected to operate for a long duration of time, such as a matter of years, at temperatures within a broad spectrum. Accordingly, there exists a need for optimizing the use of a detector, particularly as the conditions only become more extreme in various applications for these detectors.